The present invention relates to an ink jet printer having an ink cartridge and more particularly to a printhead unit and ink cartridge used in an ink jet printer.
A small impact applied to an ink jet printer, for example when the printer drops from a height of about 1 to 2 cm, will destroy the meniscuses in the nozzle plane of the printhead. When the ink jet printer receives an impact, the impact propagates to the printhead unit contained in the printer which causes the ink in the ink passage to begin to pulsate. Because the ink passage is substantially closed by an ink absorbing member (or filter) of the ink cartridge, the pulsation of ink is reflected from the ink cartridge and travels to the nozzles in the printhead thereby destroying the meniscuses in the nozzles. In the ink jet printers currently marketed, the meniscuses may even be destroyed when the printer is merely moved. When the meniscuses are destroyed, a variety of problems may arise including: "nozzle missing" resulting in the improper discharge of ink and the "bending" of the shooting ink drop thus causing the printhead to become soiled from leaking ink thereby affecting performance. As a result, ink jet printer manufacturers generally include in the printer manual instructions on how to manually clean the printhead after the printer has been moved. This problem is more acute for portable ink jet printers that are frequently moved. This forces the user to frequently clean the printhead to maintain acceptable printer performance.
The continuous loss of ink and the need to clean the printhead as a result of the meniscus destruction problem will adversely affect the marketability of these printers. One partial solution may be to increase the size of the ink cartridge thus providing the user with additional ink. However, increasing the size of the ink cartridge makes it difficult to meet the market demand for reduced printer size and portability.
Accordingly, it is desirable to have a printhead unit for use in an ink jet printer in which the meniscuses of the nozzle plane are not destroyed on impact.